Computer won't post after slightly overclocking GPU

[heroicmonster]

My gtx 970 was staying pretty low on temperature even under load so I decided to give it a slight overclock. Using the Asus GPU tweak, I went for 1350 clock speed and 7600mhz memory without changing the voltage at all. I used heaven to benchmark for about 40 minutes and I was happy that I had no graphic errors or my computer locking down. After about 3 minutes of stopping the benchmark I was closing out windows when my screen went black but my computer was still on and running perfectly fine, GPU still working. Now whenever I try to boot my computer, it doesn't post or give any video output at all. I tried to boot without my GPU and now the green led on my case actually flashes but with my GPU seated and connected, it gives no light whatsoever

Mobo Asrock 880 GMH/U3S3
Asus Strix gtx 970
600W Thermaltake PSU
8gb ram

 

[i7Baby]

Asus Strix gtx 970 overclcoking - http://www.hardocp.com/article/2014/11/03/asus_gtx_970_strix_directcu_ii_video_card_review/3#.VX-ZPfmqpBc

Can you boot into Safe Mode? http://windows.microsoft.com/en-au/windows/advanced-startup-options-including-safe-mode#1TC=windows-7

 

[heroicmonster]

Asus Strix gtx 970 overclcoking - http://www.hardocp.com/article/2014/11/03/asus_gtx_970_strix_directcu_ii_video_card_review/3#.VX-ZPfmqpBc

Can you boot into Safe Mode? http://windows.microsoft.com/en-au/windows/advanced-startup-options-including-safe-mode#1TC=windows-7

No I cannot boot into safe mode. Usually when my PC boots it gives a beep once it successfully posts. Now it just boots with no beep at all and no video output, even when trying to use the integrated graphics card.

 

[i7Baby]

Disconnect the OS drive and see if it posts.

 

[heroicmonster]

Disconnect the OS drive and see if it posts.

Still no post which leads me to believe this may be a PSU or motherboard issue as I have already tried a different GPU.

 

[i7Baby]

Time to go through Tom's checklist - http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

 

[Saga Lout]

There is a duplicate thread on this subject but the Merge facility has fallen over.

http://www.tomshardware.co.uk/answers/id-2684116/computer-post-slightly-overclocking-gpu.html#16063178

 

[heroicmonster]

Time to go through Tom's checklist - http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

I went through the checklist but still nothing. I think it is either my PSU or mobo but I guess the only way to see would be to use another tested PSU.

 

[heroicmonster]

Alright I'm updating this thread incase someone has the same problem.The problem turned out to be my PSU, tested a new one on my PC and it booted up just fine. Replacing it soon